Article from NOLA.com-INTERESTING!!! N.O area s2k'ers read!

[LaPlaceFF]

Evacuation is game plan for storms
Models predict severe flooding outside areas protected by levees
Friday, June 25, 2004
By Mark Schleifstein
Staff writer
Emergency preparedness officials from throughout southeast Louisiana said Thursday that they will urge more residents to evacuate in anticipation of Category 1 or 2 hurricanes than in the past, after seeing new computer modeling that shows such storms will cause extensive flooding in the New Orleans area.

Although most areas within hurricane flood protection levees still will be protected from a Category 1 storm, the rapid growth of housing developments outside the levees on the West Bank and in areas of St. Charles, St. John and other parishes to the west of New Orleans will require more frequent evacuations, said Tab Troxler, director of emergency planning for St. Charles Parish.


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More troubling are the new model results showing that all areas inside and outside the levees, except parts of New Orleans, could be flooded by storm surge from some slow-moving Category 2 storms, with winds of between 96 mph and 110 mph, emergency officials said. In some scenarios, water could reach New Orleans by moving south from Lake Pontchartrain through St. Charles Parish to the Mississippi River levee, where it would flow east through Metairie and into the city.

Water also could top a levee in eastern New Orleans along the Mississippi River-Gulf Outlet and cause a small amount of flooding, according to the model.


Attitude adjustment

Troxler said the model indicates it's time to change the public's attitude toward evacuating during smaller hurricanes.

"The psychology here has been that if you live in New Orleans, you ride these storms out," Troxler said. "But that's not what we want the public to think anymore."

Jefferson Parish emergency preparedness director Walter Maestri said the models also indicate that emergency officials will have to direct people to travel farther north to reach safety from a storm surge because a surge of 15 to 17 feet could be pushed into Ascension and Livingston parishes during a Category 2 storm.

Wil Shaffer, a designer of the National Weather Service's model called SLOSH, an acronym for Sea, Lake and Overland Surge from Hurricanes, said his latest version takes into account updated maps of the state's eroding coastline. But it also adds two feet of water to its estimates to account for a potential 1-foot high tide, rising sea level, subsidence, and weather and Gulf of Mexico current anomalies that have in the past caught hurricane forecasters unaware.

One such anomaly several years ago created higher-than-normal water in the Gulf of Mexico because of clockwise water currents interacting with the counterclockwise winds of a hurricane. The result was a higher storm surge than expected along the Texas coast.

Shaffer presented emergency officials Thursday with computer maps showing the combined worst-case flooding from as many as 5,000 different hurricane paths crisscrossing the coastline.

The graphic is made up of individual squares colored to indicate the maximum water height occurring as a result of any of the individual hurricane paths.


Sinking benchmarks

It showed that almost all areas outside of hurricane levees could be flooded with as much as 9 feet of storm surge from one of the many different slow-moving Category 1 hurricane paths. And slow-moving Category 2 hurricanes could flood many areas inside levees, including downtown and lakefront New Orleans and parts of eastern New Orleans.

The maps are designed to help emergency preparedness officials measure the risk of flooding and determine when to order evacuations, decisions that often must be made 24 hours or more before the path of a hurricane is known.

In many cases, such decisions must rest on whether evacuation routes will be covered with water.

Not included in this latest version of the model are even newer estimates of the actual height of levees and other land features, which are being developed by researchers at Louisiana State University for the National Geodetic Survey.

Researcher Roy Dokka said many of the official benchmarks used to set the heights of levees have sunk between 6 inches and 2 feet since the last time they were calibrated 10 or 20 years ago. The information is being used by the Army Corps of Engineers to determine whether levees need to be raised in various locations and also to identify hurricane evacuation routes that will flood well in advance of a hurricane coming ashore.

Troxler said he is not concerned that the new information will cause panic in the community. Indeed, he said a little panic might be good.

"If 20,000 more people panic and buy flood insurance, is that a bad thing?" he asked. "If 15,000 more people leave the area in advance of a hurricane, is that a bad thing? I'd love to see the public panicking and buying flood insurance, or deciding to leave next time, whether or not they would have left for such a storm in the past."

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[bevgo]

I think a lot of us know the danger of flooding in the New Orleans area. Does that mean we will take a storm seriously? I really doubt it. You have 3 tupes here, a large number that say they always turn when they are comming this way and I will take my chances, the ones that run before amnyone even suggests the need and the group that watch and wait and make actual preperations to go or stay depending on need. I am sure that is true for all our hurricane vunerable areas. I am gettintg out this year if we are threatned if at all possible.

[Guest]

Wow!!! Are these maps online??

[LaPlaceFF]

Wow!!! Are these maps online??

If you are talking about the SLOSH maps, they are not....I tried looking for them myself. I've seen a book of the SLOSH maps years ago when i worked at the OEP in my hometown of Gramercy, LA. Let me tell you that book is huge...poster size pages.

[Janie34]

Thats a shame, I'd really like to get a look at some of those maps.

[Guest]

Try this.

Slosh model.
http://www.nhc.noaa.gov/HAW2/english/surge/slosh.shtml

[Janie34]

Oooh, okies. Thanks for the link!

[Hurricanehink]

Ooh, the worst of it looks would be near Mobile Bay (I believe that is what it's called). Let's just hope the U.S.'s streak of fairly good luck will continue, as it has for the past 12 years. I know we got it bad from numerous storms, but considering how bad they could have been.... OK I'm rambling. Cool link!

[Guest]

No I know the slosh model is not available online. What I'm looking for are for maps dipicting the potential storm surge along coastal areas of the U.S.
I know that HurricaneTrack has created maps for N.C., but are there any for La, Tx, Al, Ms, and all of Fla. There are a few online for portions of Fla., then of course north along the Eastern Seaboard.
I have a link at HH that will give the potential tide data, including Storm Surge. This was used last year during Hurricane Isabel.

[wx247]

Wow...incredible article. Thanks for sharing. It would indeed be interesting to see the storm surge maps for the Gulf Coast, especially from the panhandle eastward towards the Houston area.

[PTrackerLA]

I can remember seeing storm surge predictions on tv the night before Lili hit and it showed the water reaching all the way up to basically a few miles south of here, not a good feeling to see when you've already decided to stay. Luckily she weakend.